It has been known that crossing apparatus can be arranged between vehicles coupled with one another in an articulated manner in order to enable people to cross over from one of the vehicles to the other. To make it possible for these people to cross unaffected by environmental conditions, it is now generally common practice to surround the crossing apparatus with a crossing protection apparatus. Bellows are most frequently used as crossing protection apparatus.
A turning platform, which is supported on the coupling apparatus and rotates in a cutout, which is surrounded by the floors of the two vehicles coupled with one another, is frequently used as the crossing apparatus in vehicles which must travel through sharp curves. This solution has proved to be successful especially in articulated buses. When traveling through sharp curves, especially on rather bad roads, considerable relative movements are generated between the turning platform and the floor areas surrounding it, as a result of which a considerable gap is necessary between the turning platform or platform and the floor areas surrounding it. This gap represents an appreciable source of hazard, and it must therefore be covered, i.e., it must not be made accessible to people during regular travel. This applies, in particular, to the area between the turning platform and the bellows, because the distance between the turning platform and the bellows can be kept relatively small only in the apex area of the turning platform, and it increases with increasing distance from the apex area. Accepting the gap between the turning platform and the floor cutouts surrounding it as tolerable and limiting the efforts to cover the gap between the turning platform and the side walls of the bellows has therefore become general practice.
A frequently encountered solution to covering the gap is an apron between each side wall of the bellows on one side of the annular gap and the platform on the other side of the annular gap. Measured from the platform, such an apron has a height approximately corresponding to one third of the side wall; it is fastened to the bellows at the top end, and it opens at a short distance above the top side of the platform. To make the apron as unobtrusive as possible, it is folded corresponding to the bellows in some prior-art solutions, i.e., it has the shape of the bellows or of an accordion-type bellows.
The bellows and the apron consist of relatively narrow material strips of coated fabric, and two consecutive strips of material each are connected to one another along two abutting longitudinal edges. The connection is frequently performed by bonding, sewing with clamping frames, and a plurality of these methods are frequently employed additively. The association of an inner or outer frame, though not with each fold, but in a defined sequence, is generally common, so that a plurality of edges with seams or bonded strip edges are followed by an edge which is held in a frame. The bellows can be prevented as a result from changing its contour in an unacceptable manner, especially from sagging between its ends, but, on the other hand, the deformability of the bellows, which is to be required in view of the travel of the vehicle, is not excessively reduced.